If your Navien is flashing an error code, shutting off mid-shower or not heating, we diagnose and repair it. We offer same day service across all of Queens, and in Forest Hills, Rego Park, Kew Gardens, Flushing, and Middle Village, we aim to be at your door within an hour for emergencies. You get a written flat-rate price after diagnosis and before any work begins, and our labor carries a 90-day guarantee.
We repair Navien NPE-series condensing tankless water heaters, including the NPE-A2 and NPE-S2. Below is what each error code points to, what we check first, what Navien's warranty covers, and what repairs cost.
| Code | What it indicates | What we check first |
|---|---|---|
| E003 | Ignition failure | Gas supply and pressure, igniter, flame rod, burner, ignition control |
| E004 | False flame detected | Flame-sensing circuit, power-cord grounding, vent blockage |
| E012 | Flame loss while running | Gas pressure and line size, regulator, dirty intake air filter |
| E016 | Heat exchanger overheating | Clogged cold-water inlet screen, partly closed valve, scale, flow |
| E030 | Exhaust overheating | Vent restriction and exhaust flow |
| E110 | Air-pressure / exhaust fault | Vent termination (winter icing), air intake, blockage |
| E434 | Water adjustment valve fault | Valve and wiring |
| E515 | Control board (PCB) fault | Grounding first, then the board |
| E760 | Flush / service alarm | A heat exchanger flush is due. It's a reminder, not a failure |
If you smell gas, leave the building and call 911 and your gas utility from outside. Otherwise, one safe check is whether your gas shutoff valve is open and your other gas appliances work. Don't keep resetting the unit or open the cabinet.
Symptom | Likely causes | What we do | Typical price |
|---|---|---|---|
| No hot water, no code | Closed gas or water valve, power, flow too low to fire, clogged inlet screen, failed flow sensor | Check supply, power and screen, test the flow sensor | Diagnostic $75–$125; flow sensor $200–$325 |
| Hot water fades or shuts off mid-use | Restricted flow, scale, overheat protection | Clean screens, test flow, descale | Descale $150–$250 |
| Cold burst between uses | "Cold-water sandwich," recirculation setup | Check the recirculation loop and pump | Pump or valve $400–$700 |
| Water at the base of the unit | Fitting, relief valve or condensate drain | Trace the actual source before touching anything | Condensate neutralizer $175–$275 |
| Hot, but never hot enough in winter | Often not a fault (see below) | Check demand against the unit's winter output | Diagnostic $75–$125 |
Navien publishes heat input ranges and maximum flow ratings for the NPE-2 line. Those flow figures correspond to roughly a 35°F temperature rise (our calculation). In January, Queens supply water arrives around 40–45°F and you want 120°F at the tap, so the unit has to add about 75°F. Flow equals heat input × efficiency ÷ (500 × temperature rise). At a 75°F rise:
| Model | Rated max flow | Approx. winter flow |
|---|---|---|
| NPE-150S2 | 6.8 GPM | 3.0 GPM |
| NPE-180A2 / S2 | 8.4 GPM | 3.8 GPM |
| NPE-210A2 / S2 | 10.1 GPM | 4.6 GPM |
| NPE-240A2 / S2 | 11.2 GPM | 5.1 GPM |
Showers commonly use 1.5–2.5 GPM each. A unit that handles one shower but fades with two may be working as designed. We measure before we recommend any part.
Navien publishes heat input ranges and maximum flow ratings for the NPE-2 line. Those flow figures correspond to roughly a 35°F temperature rise (our calculation). In January, Queens supply water arrives around 40–45°F and you want 120°F at the tap, so the unit has to add about 75°F. Flow equals heat input × efficiency ÷ (500 × temperature rise). At a 75°F rise:
| Model | Rated max flow | Approx. winter flow |
|---|---|---|
| NPE-150S2 | 6.8 GPM | 3.0 GPM |
| NPE-180A2 / S2 | 8.4 GPM | 3.8 GPM |
| NPE-210A2 / S2 | 10.1 GPM | 4.6 GPM |
| NPE-240A2 / S2 | 11.2 GPM | 5.1 GPM |
Showers commonly use 1.5–2.5 GPM each. A unit that handles one shower but fades with two may be working as designed. We measure before we recommend any part.
NPE-A2 models include an internal circulation pump and a 0.5-gallon buffer tank. The NPE-S2 doesn't include a pump, so recirculation on it needs an external one. Navien's ComfortFlow system on the A2 is designed to address the cold-water sandwich. We identify your model and recirculation setup before diagnosing, because they determine which parts and settings are involved.
For residential installations, NPE units carry 1 year of labor, 5 years on parts and 15 years on the heat exchanger, falling to 3 years on parts and 5 on the heat exchanger when recirculation is uncontrolled.
| Residential application | Labor | Parts | Heat exchanger |
|---|---|---|---|
| Standard or controlled recirculation | 1 year | 5 years | 15 years |
| Uncontrolled recirculation | 1 year | 3 years | 5 years |
Navien warranty documents tie coverage to installation by a properly licensed plumber or contractor, operation per the manual, and genuine Navien repair parts. Within the warranty period, Navien replaces a defective part or heat exchanger at its option, and labor payments need its prior written approval. Read your unit's warranty for exact terms. Before quoting, we check your serial number, install date and recirculation setup, and we tell you in writing what, if anything, you'd owe.
Repair is usually right for sensors, igniters and flame-sensing parts, inlet screens, condensate traps, recirculation pumps and valves, and control faults.
Replacement deserves a conversation when the heat exchanger has failed outside warranty, the same faults keep returning, or the unit can't meet your household's winter demand. If you reach that point, see our tankless water heater installation page.
| Service | Typical price |
|---|---|
| Diagnostic and error-code reading (waived when we repair the same visit) | $75 – $125 |
| Inlet filter cleaning | Included in diagnostic |
| Annual descaling and service | $150 – $250 |
| Flame rod cleaning or replacement | $175 – $275 |
| Flow sensor replacement | $200 – $325 |
| Ignition control board replacement | $350 – $600 |
| Modulating gas valve | $300 – $550 |
| Condensate neutralizer replacement | $175 – $275 |
| Venting inspection and cleaning | $150 – $225 |
| Vent repair or reconfiguration | $250 – $500 |
| Recirculation pump (external pump on NPE-S2) | $400 – $700 |
| Heat exchanger replacement | $700 – $1,400 |
Parts carry the manufacturer's warranty, and our labor is guaranteed for 90 days. Anything not listed is quoted in writing after diagnosis and before work begins. Within Navien's warranty period, the part itself is Navien's responsibility.
You call with the code. Tell us the full code and your model if you know it.
We test before touching anything. We read the code, then check gas pressure, water flow, the inlet screen, the intake filter and the venting.
You get a written price before any work begins.
We repair and retest, then record the readings.
You get the paperwork. [We support warranty claims where your unit is covered.]
We offer same-day Navien repair across all of Queens, including
Ignition failure. The unit couldn't light the burner or prove a flame. Check that the gas shutoff is open and your other gas appliances work. If you smell gas, leave and call 911 and your gas utility. Otherwise call us with the full code.
For overheat codes such as E016 and E030, guides suggest turning the unit off for about 30 minutes, then restarting. A code that comes back means something is restricting flow or venting, and repeated resets only hide it.
Common causes are a closed gas or water valve, a clogged inlet screen, a failed flow sensor, or an ignition fault. The display code tells us which to check first.
That's the cold-water sandwich. The NPE-A2's built-in pump and buffer tank are designed to address it, while the S2 needs an external pump. We check the loop's setup first.
Often parts are, within 5 years (15 on the heat exchanger) under standard conditions, but labor coverage is 1 year and needs Navien's approval. We check your serial number and recirculation setup before quoting.
Navien recommends a professional. If you try it, follow your unit's manual and shut off gas, water and power first.
Diagnostics run $75–$125 and are waived when we repair on the same visit. Most component repairs fall between $175 and $600, and an annual descale is $150–$250. You get the exact price in writing first.
Yes. We identify your model and recirculation setup first.
Yes, call us with the model number.
Licensed NYC plumber, written price first, 24/7